Oh dear God! 318 stroker
Ah, what the heck, build what ever you want. Do your homework and search for the proper parts. I have read about some strong 318/390's here. Just a few. Most aren't that attached to the original Teen though. Remember, if you modify it it won't be original any more. Pull it, stuff it in the corner, and build a 360/408+ Magnum stroker. (I can't believe I said that) I rebuilt the 273 in my 66 with no regrets. I like the 318 in my 70 Swinger so much I might not even out a 4 barrel on it. I have a LD4B, a 650 AVS2 , 68 340 manifolds, and even a set of Speedmaster heads. I might just leave it all as originally designed. No reason to mess with perfection.